1. Field of Invention
The present invention relates to a method and an apparatus for making a color filter used in an optical device, such as a liquid crystal display. The present invention also relates to a method and an apparatus for making a liquid crystal display having a color filter. Furthermore, the present invention relates to a method and an apparatus for making an electro-luminescent (EL) device for display using an electro-luminescent layer.
Also, the present invention relates to a method for discharging a material, and an apparatus for discharging thereof. Further, the present invention relates to electronic apparatus with a liquid crystal display device or an electro-luminescent device manufactured by the methods.
2. Description of Related Art
Currently, display devices, such as liquid crystal devices and EL devices, are increasingly used in the display sections of electronic devices, such as cellular phones and portable computers. Also recently, an increasing number of display devices are employing a full-color display. Full-color display in the liquid crystal devices is, for example, achieved by leading the light modulated by liquid crystal layers to pass through color filters. The color filters are formed by, for example, aligning dots of filter elements of red (R), green (G), and blue (B) in a predetermined configuration, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like.
In order to achieve full-color display in an EL device, dots of red (R), green (G), and blue (B) electro-luminescent layers (EL layers) are aligned in a predetermined pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern, on the surface of a substrate made of glass, plastic, or the like. Each of the EL layers is then sandwiched by a pair of electrodes so as to form a pixel, and the voltage applied to these electrodes is controlled according to the individual pixels so as to make the pixels emit desired colors and to achieve full-color display.
Conventionally, patterning of the R, G, and B filter elements and patterning of the R, G, and B pixels of the electro-luminescent device have been performed by photolithography. However, photolithography is a complex and costly process because the process consumes a large amount of colored materials, photoresists, and the like.
In order to overcome these problems, the use of an inkjet method in which the filter element and electro-luminescent layers aligned in the dot-matrix are formed by discharging in a dot-matrix a filter material, an electro-luminescent material, or the like, has been suggested.
Referring to FIGS. 22A and 22B, a plurality of filter elements 303 arranged in a dot matrix are formed by means of an inkjet method in the inner regions of a plurality of panel regions 302 defined on the surface of a mother substrate 301, i.e., a large-size substrate made of glass, plastic, or the like.
Here, as shown in FIG. 22C, an inkjet head 306 having a nozzle line 305 including a plurality of nozzles 304 arranged in a row performs first-scanning a number of times (two times in FIG. 22B) relative to one panel region 302 as shown by arrows A1 and A2 in FIG. 22B. Meanwhile, during the first-scanning, ink, that is, a filter material, is selectively discharged from the plurality of nozzles 304 so as to form filter elements 303 at the desired positions.
The filter elements 303 are formed by arranging colors such as R, G, and B, in an appropriate pattern, such as a striped pattern, a deltoid pattern, or a mosaic pattern. The process of discharging ink using the inkjet head 306 shown in FIG. 22B is performed as follows: three of the inkjet heads 306, each of which discharges one of three colors from among R, G, and B, are prepared in advance; and these inkjet heads 306 are used sequentially to form a pattern of three colors, such as R, G, and B, on one mother substrate 301.
As for the inkjet head 306, generally, there is a variation between the amounts of ink discharged from the plurality of nozzles 304 constituting the nozzle line 305. Accordingly, the inkjet head 306 has an ink-discharge characteristic Q shown in FIG. 23A, for example, wherein the discharge amount is largest at the positions corresponding to both ends of the nozzle line 305, next largest at the position corresponding to the middle thereof, and least at the other positions.
Thus, when the filter elements 303 are formed using the inkjet head 306 as shown in FIG. 22B, dense lines are formed at positions P1 corresponding to the end portions of the inkjet head 306 and/or at positions P2 corresponding to the middle of the nozzle line, as shown in FIG. 23B, impairing uniformity of the in-plane light transmission characteristics of the color filter.